Well, the articles I read pinpoints it to next year, since Micron GDDR6 isn't readily available. They mentioned that GPUs using GDDR6 will come next year, hence the answer. Maybe they'll go the 750 Ti route with Volta and release the slower card first this time. Who knows~
Try searching Youtube for RandomGamingHD channel. He got himself a GT 1030 and he shown that it has no trouble playing even GTA 5, so LoL is probably going to hit triple digits at 1080p. He also played Overwatch and Dota2 and both can be set to maximum details at 1080p with more than 40fps on Overwatch.